Crop diversity effects on productivity and economics: a Northern Great Plains case study

Increasing crop diversity has been proposed to increase the sustainability of cropping systems. If producers are to adopt these systems, they should also be economically viable. In this study conducted near Mandan, North Dakota, four no-till cropping systems with varying levels of crop diversity were evaluated over a 12-yr period to quantify system effect on crop productivity, input use, production costs, and economic risks and returns. Cropping system treatments included a small grain–fallow rotation (SG–Fallow) and a continuous spring wheat ( Triticum aestivum L.) rotation (Cont SW) as baseline low-diversity rotations, a small grain–winter wheat ( T. aestivum L.)–sunflower ( Helianthus annuus L.) rotation (SG–WW–Sun), a 5-yr rotation (Five Year) and a dynamic rotation (Dynamic). The SG–Fallow rotation was significantly less productive and less profitable on average than the other rotations, as measured by gross returns and net returns, respectively. However, SG–Fallow also used significantly less inputs than the other rotations. Production costs for the Cont SW and SG–WW–Sun rotations showed a significant increasing trend over time, while production costs for the Five Year rotation showed a significantly lower and slight decreasing trend over the period, with cost trends for the SG–Fallow and Dynamic rotations intermediate to these. Net returns tended to increase and relative economic risk tended to decrease as crop diversity increased from SG–Fallow and Cont SW to SG–WW–Sun, Five Year and the Dynamic system. Results from this study suggest that more diverse rotations can maintain or increase crop productivity and enhance economic viability.